In a compressor housed inside, for example, an outdoor unit of an air conditioner, various types of soundproof means are provided for the purpose of suppressing leakage of operating noise generated by the compressor to the outside in related art. For example, Patent Literature 1 discloses that a mold-processed felt material is attached to an outer surface of a compressor of an outdoor unit and an aluminum plate is further bonded to an outer surface of the felt material to be used as a soundproofing material.